In the current deployed cellular telecommunications networks, the usage of Packet Switched (PS) traffic for Packet Services has boomed. A similar trend is apparent in the take up of different mobile client applications (“apps”) and the usage of cellular data connectivity as a mobile alternative to fixed line broadband network access, such as Asymmetric Digital Subscriber Line (ADSL)—often referred to a “mobile broadband”.
The Radio Access technologies adopted in cellular telecommunications networks are conveniently discussed in terms of “generations”. Second generation (2G) technologies include GSM, GPRS, D-AMPS and CDPD, for example: while third generation (3G) technologies include UMTS, CDMA2000 and WD-CDMA for example. In certain “Beyond 3G” scenarios sometimes referred to as “4G”, Long Term Evolution (LTE) technology is introduced. The “earlier” generations have not in general fallen into disuse and it is typical that LTE technology is implemented in cellular network architectures that already provide access using existing 3G (UMTS) and 2G (GSM-GPRS) technologies (with substantially overlapping geographical coverage).
At the moment, when each of these three radio technologies (GPRS, UMTS, LTE) is available for users, every User Equipment (UE) would, by default, camp on the technology assigned the highest priority level by the mobile network operator, i.e. LTE over UMTS over GPRS. A UE is only typically redirected to another technology where there is a high likelihood of losing and/or coverage or capacity. This criterion for redirecting a user to a radio technology is not optimum for most of the applications, as the requirements (e.g., latency sensitivity) for each application is different.
Subscribers who wish to access mobile packet services from a portable computing device, such as a laptop PC or a netbook, have a number of options: the portable device may have a suitable wireless wide area access network (WWAN) module or embedded cellular radio access modem; he may choose to couple his device physically or via a short range wireless technology (such as Bluetooth® or Zigbee®) to a cellular communications device; or he may use a dedicated external cellular modem, which couples to the portable device via an existing interface such as PCMCIA or USB. It is known that such access devices may be adapted to provide access to more than one different radio access networks—while being active on only one access network at any one time: thus an LTE-enabled USB modem dongle may also have 2G and/or 3G capabilities.
Subscribers may wish to avail themselves of more than one of these packet service access options simultaneously. In one typical arrangement, the user obtains two commercially available dedicated cellular modem devices, typically USB dongles, and couples both modems to his computing device.
A mechanism is known in the art that allows such a subscriber to aggregate the data capacity of two or more packet service access devices. In essence, this mechanism makes it possible to emulate, for example, a connection aggregating 3G and LTE data connections. Clearly, building a hybrid device that combines two or more packet service access devices from scratch would require considerable development efforts (including standardisation in 3GPP). To aggregate the 3G and LTE data connections of the example, the pragmatic approach is thus to use one commercial cellular modem device (henceforth referred to simply as a “terminal”) that is 3G capable and one commercial terminal that is LTE capable.
This pragmatic approach does however mean that the two terminals are operating independently just as they would for two different subscribers. In order to manage a hybrid connection using these two commercially available terminals, it is would be desirable to have some level of control over both terminals in order to ensure that the best possible data connection is available to the user at all times whatever the coverage scenario and technology the devices are operating on.